200r4 trans shift point upgrade



200r4 trans shift point upgrade

Postby grumpyvette » June 22nd, 2014, 4:26 pm

http://www.transmissioncenter.net/2004rtip.htm

viewtopic.php?f=39&t=617&p=20099&hilit=cable+adjustment#p20099

http://www.summitracing.com/parts/TRG-200-4R-HD2/

http://www.converter.com/ (these guys have a reputation for building a decent quality stall converter)

http://www.summitracing.com/parts/tci-2 ... 7AodulIAig

DON,T IGNORE READING LINKS

hotrodders wrote:How to change auto shift timing on 200R4
When you upgrade to a 200R4 OD transmission to get the benefits of the 0.67 overdrive, it is rare that the automatic shifting sequence occurs at the proper speed. Most likely you have lower rear end gears and a cam so you want the shifts to occur at a higher RPM but the donor tranny is likely set up for a grocery getter and results in 1-2, 2-3 shifts way too soon for your setup. Thus you are stuck with manual shifting which is fun but there are times you want to set it in drive and run it automatically.

A lot of people suggest changing the shift points by adjusting the throttle cable. DON'T DO THAT! That cable needs to be set properly and left alone. It is the governor that sets the shift timing and you have to modify it.

We did ours on our '59 El Camino running a 307 w/ corvette cam; 283 PowerPack heads. We put 3.54 gears in the rear so our auto shifts were occurring @ ~1000rpm lugging the engine badly.

We bought a couple spare governors from PATC Automotive who specializes in 200R4 trannys.

http://www.transmissioncenter.net/200-4r.htm

I am giving them a plug because their authentic GM parts governors are less than $10! We bought two to play with.

It is a hassle to do this modification because you need to take the pan off to get at the governor. There are YouTube videos on doing that step so look it up if you don't know where the governor is. It is an easy swap. Here is a good video

https://www.youtube.com/watch?v=iZPRZire8vM

https://www.youtube.com/watch?v=Ry6bVpEcO7c

Image
Photo 1 shows the modified governor on the left and the stock one on the right. We took a huge amount of weight off the modified one (power hacksaw and files) but we took the design from a picture of a governor from a Grand National Buick. Plus we still have two more to play with if we screwed this one up. We cut half the skirt off the small weight and ground the top of the large one even with the top of the small one, about 1/8".
Image
Photo 2 shows an end view of the small weight. These things come apart very easily knocking out the pin at the base of the weights. Watch where the two ball bearings go! When putting them back together, 'glue' the bearings in their holes w/ Vaseline.
Image
Photo 3 shows a couple more modifications we made. First we took out the spring in the big weight leaving the spring in the small one. We took our cue on this again from the Grand National Buick version. Second, we brazed a short nail in the spring hole in the small weight. Word is that that spring has a tendency to hop out on hard shifts so this is a common hi performance mod.
Image
Photo 4 shows another view of the nail.

There are other sites on the web showing how to calibrate the speedometer by changing our the big plastic barrel gear on the shaft of the govern with the speedo gear that is removed by taking off the speedo cable at the back of the tranny. Do that while you are doing this. I think PATC sells the cheapest gears too. They have a ratio calculator on their site so if you know your tire diameter and rear end ratio, you get the perfect speedo ratio.

Oh, we ended with perfect shift points for the street; ~2000rpm @ 1-2 and 3000rpm @ 2-3. We haven't tried it yet but I assume at WOT the shifts will rise accordingly to higher in the power band.


IF YOU CAN,T SMOKE THE TIRES AT WILL,FROM A 60 MPH ROLLING START YOUR ENGINE NEEDS MORE WORK!!"!
IF YOU CAN , YOU NEED BETTER TIRES AND YOUR SUSPENSION NEEDS MORE WORK!!
grumpyvette

User avatar
Site Admin
Site Admin
 
Posts: 14105
Joined: September 14th, 2008, 1:40 pm
Location: florida

Re: 200r4 trans shift point upgrade

Postby Indycars » June 22nd, 2014, 6:02 pm


Good info Grumpy ..... thanks!

Rick
Too much is just enough!!!

- Check Out My Dart SHP Engine Project: viewtopic.php?f=69&t=3814
- Need a Dynamic Compression Ratio Calculator: viewtopic.php?f=99&t=4458
Indycars

User avatar
Forum Admin
Forum Admin
 
Posts: 4424
Joined: May 25th, 2010, 8:58 am
Location: Yukon, OK

Re: 200r4 trans shift point upgrade

Postby busterrm » June 23rd, 2014, 4:15 am

Hey Rick, I believe I can do the mods with a small angle grinder. With that metal being a governer I bet its pretty hard and you probably can't do it with a hacksaw. Be a good reason to ride up to OKCity and get the heebeegeebees scared out of me in the T bucket!
Bob
2007 Chevy Silverado
1976 Chevy Nova
2008 Harley - Davidson Sportster 1200 Custom.
If I can't smoke the tires I want more!!!
busterrm

User avatar
 
Posts: 925
Joined: December 9th, 2011, 4:58 pm
Location: Wichita Falls, Texas

Re: 200r4 trans shift point upgrade

Postby grumpyvette » June 23rd, 2014, 5:44 am

7y1vette wrote:Setting the TV cable correctly is the most important aspect of installing a 200-4R or 700R4 transmission. The transmission uses TV pressure (Throttle Valve pressure) to regulate the shift timing and firmness properly. As the TV cable is pulled out of the trans, TV pressure increases. So, the further you press on the accelerator, the firmer and later the range shifts are made.

The placement of the cable connector pin on the carb throttle linkage is important. Selecting the best mounting hole in that linkage for the connecting pin (or redrilling a new one) is the first step in getting that cable to work properly. It would be difficult to tell you all the steps required to do that, but what needs to happen is that the TV cable should be at the start of its travel when the throttle is "closed" and very near the end of its travel when the throttle is at "full open" position. If you were to connect a pressure gauge to the TV pressure port on the left side of the transmission, you could watch the increase/decrease of pressure as the cable is moved in and out. Ideally, you would want the cable to be adjusted so that at "closed" throttle, the TV pressure is just at the start of increasing pressure; and at "full open" throttle, TV pressure has just reached its maximum point (still prior to the end of cable travel). THE CABLE SHOULD NOT BE 'LOOSE' OR REACH ITS FULL RANGE OF TRAVEL AT ANY TIME once it has been properly adjusted to the carb throttle linkage.

Hopefully, you will be able to understand the concept of the TV cable and its relationship to the throttle cable/linkage. If you do hook up a pressure gauge to the trans, you can measure how much cable travel there is from the onset of pressure increase to maximum TV pressure. That distance is how far (linear distance) the cable attachment pin must move from "closed" throttle position to "full" throttle position on the carb linkage. Then, adjust the length of the cable so that it is just at the beginning point of TV pressure increase at the "closed" setting. That should set it up correctly.

If you need other details or clarification, put another update post to this thread or send me a PM with your questions.

P.S. IMPORTANT!!! If you are working with the carb throttle while on the car, make sure that you disconnect the accelerator pump arm so that it is not constantly dumping fuel into your intake while exercising the throttle. If you do not disconnect it (drive roll pin just far enough to release that lever arm on a Q-Jet carb), raw fuel will collect in the manifold and it could explode when you first fire the car!!!



http://www.jakesperformance.com/TV_Cabl ... _Info.html
jake wrote:Everybody has heard about the importance of properly setting up the TV cable to ensure you don't damage your GM overdrive transmission. This is absolutely true and it IS an important step in properly installing your overdrive transmission. Our goal is to ensure you can make this happen with minimal hassle. We've helped hundreds of enthusiasts do this successfully.

While it is important it is NOT rocket science. The transmissions that use the TV systems started in the mid 70's and have been obsolete in OEM vehicles for over 15 years. The average hotrodder can easily accomplish this task either by using commercially available parts or by using their fabrication skills and ingenuity and in some cases even some stock parts.

We'll talk about some critical steps to doing this.

1. Proper TV cable adjustment. This is simple. You are ideally looking for the TV plunger to be fully "depressed" into the valve body. Depending on the calibration of the TV plunger spring and the transmission hydraulics you may not need to be completely depressed but in all cases you should be very near it.

2. Proper TV geometry at the throttle linkaqe. This is the most often overlooked step to getting the TV cable properly setup. It's relatively simple to check though and in many cases is an easy fix.

These two things are what must be correct.
Now we will show you how.

Adjusting the TV cable is a pretty simple procedure. If you hold the carburetor or throttle body at WOT (or better yet have a helper do so) you want to activate the release on the cable. These are a button type as used by GM on the cables we use at Jake's Performance. Some use a clip that must be pried "out" of the cable and then pressed back in to lock the cable adjustment. In either case, unlock the cable adjustment and pull the cable sheath AWAY from the carburetor but towards the transmission or rear of vehicle. You want the wire portion of the cable to be tight with no slack. Lock the release now.
Verify that the cable is tight while the throttle is still held wide open (with the engine not running!).

Let the throttle return to the idle position. Feel the wire portion of the cable. It will usually still have some tension, it will alays have tension while the engine is running.

This is your baseline TV cable setting. It should be very close. You will not have any further adjustment to tighten it. You CAN however slightly loosen it if the shifts are late and hard indicating high line pressure.

One thing we'll mention, all TV cable brackets need to be rigid and not flex during normal throttle operation.

Now,
We've covered the basic TV cable adjustment. We HIGHLY recommend using a transmission pressure gauge to ensure proper adjustment and transmission pressures.

What you are looking for on a gauge is instant pressure rise anytime the TV cable is moved. Particularly from the idle position. The average GM overdrive transmission will have 65-90 psi line pressure at idle on a gauge. This should spike with slight pressure applied on the cable or if the throttle is cracked at all.

Note:
Pressures above 90 psi at idle may result in 2nd gear starts, particularly when the transmission fluid is warm. You may need to back off the cable adjustment slightly until you get down to 90 psi or less idle pressure.
As long as you have instant pressure rise on any movement of the TV cable, you will not cause damage to the transmission.

As stated earlier the TV cable geometry at the throttle linkage is often overlooked. In many cases an installed is replacing a TH350 that uses a kickdown cable and not a TV cable with their new overdrie trans and since the brackets for the TH350 kickdown cable work with the TV cable and the carb already has a stud on it, they mistakenly assume they can just hook it up, adjust it, and go.

The issue here is that the geometry on the carb linkage is not correct. It has a different radius of arc than what is needed for the TV cable. The TV cable needs a 1.093-1.125" measurement, the older TH350 kickdown is closer to 1.375".

This creates a condition where the cable is adjusted correctly but since the geometry is wrong, the overdrive transmission has correct pressures at WOT, but becomes farther away from correct with every degree of throttle less than WOT.
Not really an issue at WOT or even 3/4 throttle.

It becomes an issue just off idle, where a street car operates more often than any other throttle angle. What the pressure gauge will show you is little or no pressure spike on very slight throttle movement. This is the killer of automatic overdrives in retrofit applications.

The radius is a simple measurement that can be done with a caliper, a machinist rule, or even in a pinch a tape measure to get an idea.
You measure from the centerline of the throttle shaft to the center of the TV stud. It should be approx 1 and 1/8th inch or slightly less. We prefer to see if on the short side. 1.100".

You also want to see the TV stud rearward of center approximately 20-30 degrees. The OEM spec was 23* but this is not all that critical. It does have some effect on the rate of initial pull of the cable but a properly calibrated performance overdrive transmission will not be overly sensitive.

A picture is provided here to clarify the geometry.

Image

The importance of having proper pressure rise off idle cannot be overstated. A pressure gauge is an invaluable tool for checking this.

It isn't mandatory but it is a time saver and in some cases a transmission saver.

The reason it is so important to have instant pressure rise off idle is because every time you accelerate from a stop, you transition from idle, no load, and low pressure to off idle, accelerating load PLUS torque converter multiplication, and hopefully more pressure.

A torque converter multiplies torque from the engine to the transmission input shaft. Maximum torque multiplication occurs at stall speed. Basically as your car is leaving the stop light. A moderate V8 street engine is making decent torque just off idle, even if only 100 lb/ft, this is multiplied to 200-250 lb/ft to the input shaft. The clutches will not clamp under power without proper pressure. If they slip slightly every time you accelerate from a stop, over a couple of thousand miles they fail.

All you need is proper geometry at the carb linkage and proper TV cable adjustment for a happy overdrive transmission.
If you confirm it with a gauge, you KNOW it is correct.

Approximate pressures you want to see are posted below:
Idle or Min TV Full TV
P 70-90 psi 230-275 psi
R 230-300 230-300
N 75-90 230-275
4 75-90 230-275
3 75-90 230-275
2 230+ 230+
1 230+ 230+
IF YOU CAN,T SMOKE THE TIRES AT WILL,FROM A 60 MPH ROLLING START YOUR ENGINE NEEDS MORE WORK!!"!
IF YOU CAN , YOU NEED BETTER TIRES AND YOUR SUSPENSION NEEDS MORE WORK!!
grumpyvette

User avatar
Site Admin
Site Admin
 
Posts: 14105
Joined: September 14th, 2008, 1:40 pm
Location: florida

Re: 200r4 trans shift point upgrade

Postby Indycars » June 23rd, 2014, 10:37 am

busterrm wrote:Hey Rick, I believe I can do the mods with a small angle grinder. With that metal being a governer I bet its pretty hard and you probably can't do it with a hacksaw. Be a good reason to ride up to OKCity and get the heebeegeebees scared out of me in the T bucket!


You can definitely come up anytime to get your system cleaned out with a ride in the TBucket. :lol:

Before jumping in and making any changes I need to bone up on the subject first.

Rick
Too much is just enough!!!

- Check Out My Dart SHP Engine Project: viewtopic.php?f=69&t=3814
- Need a Dynamic Compression Ratio Calculator: viewtopic.php?f=99&t=4458
Indycars

User avatar
Forum Admin
Forum Admin
 
Posts: 4424
Joined: May 25th, 2010, 8:58 am
Location: Yukon, OK

Re: 200r4 trans shift point upgrade

Postby 87vette81big » June 23rd, 2014, 12:34 pm

Be sure to Ask Chris at CK Performance How much Line Pressure you can run safely in your 200R4 trans Rick.
Some guys have tried running 400psi peak line pressure in GM 700R4 & broken parts resulted.
Cracked or bent clutch apply pistons & blown out lip seals.

Maybe a change in stiffer accumulator springs in order.
I put the stiffest 1-2 & 3-4 Accumulator springs available in my 700R4 in the Vette.
No regrets. Firm Positive Lighting fast shifts with moderate line pressure of 290psi.
87vette81big

User avatar
 
Posts: 3278
Joined: February 28th, 2012, 12:34 am
Location: Central Illinois

Re: 200r4 trans shift point upgrade

Postby Indycars » June 23rd, 2014, 3:32 pm


Right now I'm maxing out at 240 psi at 1500 RPM and the TV cable pulled
completely out. Might be alittle low.

I will need to check and see exactly when it does shift automatically in each
gear, I'm sure Chris is going to ask.
Rick
Too much is just enough!!!

- Check Out My Dart SHP Engine Project: viewtopic.php?f=69&t=3814
- Need a Dynamic Compression Ratio Calculator: viewtopic.php?f=99&t=4458
Indycars

User avatar
Forum Admin
Forum Admin
 
Posts: 4424
Joined: May 25th, 2010, 8:58 am
Location: Yukon, OK

Re: 200r4 trans shift point upgrade

Postby 87vette81big » June 23rd, 2014, 3:45 pm

Indycars wrote:
Right now I'm maxing out at 240 psi at 1500 RPM and the TV cable pulled
completely out. Might be alittle low.

I will need to check and see exactly when it does shift automatically in each
gear, I'm sure Chris is going to ask.

I went through great lengths to Minimize eliminate fluid leaks internal.
In a 700 R4 its the Accumalator pistons & Abuse valve another Accumulator piston package.
Blueprinted all like you.
Just another GM overdrive trans of different model.
SONNEX MAKES HEAVY DUTY BILLET ALUMINUM DUAL LIP ACCUMULATOR PISTONS.
CHECK ONLINE & EBAY VENDORS.
87vette81big

User avatar
 
Posts: 3278
Joined: February 28th, 2012, 12:34 am
Location: Central Illinois

Re: 200r4 trans shift point upgrade

Postby busterrm » June 23rd, 2014, 4:39 pm

Indycars wrote:
busterrm wrote:Hey Rick, I believe I can do the mods with a small angle grinder. With that metal being a governer I bet its pretty hard and you probably can't do it with a hacksaw. Be a good reason to ride up to OKCity and get the heebeegeebees scared out of me in the T bucket!


You can definitely come up anytime to get your system cleaned out with a ride in the TBucket. :lol:

Before jumping in and making any changes I need to bone up on the subject first.

Oh I know you will read up on it, just saying I could do it with cutting wheel on small angle grinder easily
Bob
2007 Chevy Silverado
1976 Chevy Nova
2008 Harley - Davidson Sportster 1200 Custom.
If I can't smoke the tires I want more!!!
busterrm

User avatar
 
Posts: 925
Joined: December 9th, 2011, 4:58 pm
Location: Wichita Falls, Texas


Return to Drive Train and Tires: Selection and Modification

Who is online

Users browsing this forum: No registered users and 1 guest

cron